In a teamfight, it's generally best to aim Transcendent BladesTranscendent Blades to hit as many champions as possible to keep you alive, rather than directly at a single target for extra damage, as this will give you the best sustain. With proper positioning, both these effects can be achieved without having to compromise. For example, shift around to fire the blades forward into the bulk of the enemy team while also hitting the main target.

During laning, fire into as large of a minion group as possible to regain large amounts of health either to continue laning or to survive a skirmish.

If coordinated well, it also makes an effective tool for escaping ganks or failed team fights at low health. By clicking the edge of your screen and firing off a few blades, you can heal off of the enemy champions chasing you to buy time to escape.

Hiten StyleHiten Style is great for jungling. Being able to sustain herself in lane while also being able to deal true damage to neutral creeps allows her to use other runes rather than armor penetration.

When ganking as Irelia, it is important to use your abilities when they will be most effective. If you can engage your target without using Bladesurge then consider saving it in case you need to chase them. Equilibrium StrikeEquilibrium Strike can also be of greater use if it is reserved until your target starts to flee, or your health is low enough to leverage the stun to your advantage, rather than for immediate burst damage.

Buying her Mercury's Treads is highly recommended, since the effect works well with her Ionian FervorIonian Fervor, as any tenacity item boosts her CC reduction by up to 41.5/51.25/61% depending on the respective amount of enemy champions nearby.